1. Technical Field
The present disclosure concerns a device for drawing together opposite sides of an incised dura, and more particularly, to dural closing forceps for use in closing the dura after a durotomy.
2. Background of the Related Art
The dura is a tough protective membranous covering surrounding the central nervous system including the spinal cord and related nerve bundles. Surgery involving the dissection of the dura, a durotomy, is often required when operating on the brain or spine. A durotomy allows the surgeon to approach particular nerve structures for definitive dissection.
The central nervous system including the spinal cord and related nerve bundles are all constantly bathed in cerebrospinal fluid (CSF) all of which are encased by the dura. The CSF is constantly under pressure within the dura, this CSF pressure increases with certain disorders of the nervous system or by an erect posture of the head. The CSF is manufactured from circulating arterial blood passing through specialized filtration glands deep within brain cavities. The CSF then leaves the cavities and flows downward over the spinal structures by motion of the spine and pulsation of blood vessels. The CSF then flows back into the brain cavities where it is reabsorbed back into the body's circulatory system.
After the dura has been incised and the surgical procedure on the underlying nerve structures is performed, the dura must be closed to prevent any further escape of CSF. If the CSF leaks are not halted, the patient may have severe, persistent, disabling headaches. In some cases the durotomy may permit bacterial invasion resulting in life threatening meningitis. Water tight closure or sealing of durotomies is therefore an important aspect of neurosurgical practice.
Upon leakage of the CSF, nerve filaments or fragments of other, softer covering membranes are frequently flushed out and protrude beyond the margins of the durotomy. These filaments or fragments must be replaced and retained inside the dura as it is closed by the surgeon. Closing or sealing the dura after a durotomy requires retaining the filaments or fragments within the dura and holding the dural margins tightly together, aspirating the escaping fluid and obscuring blood while keeping the nerves and fragments from being caught into the closing seal and applying the sutures or clips. Optical magnification, often by a surgical microscope, is generally needed in order to complete the tedious procedure. It is quite clear that surgeons must possess considerable skill to effect a water tight closure of certain complex durotomies. Fortunately, once the dura is well closed, the margins are quickly sealed over with blood clots and-new tissue growth begins in a matter of hours permanently closing the durotomy in a matter of days.
Closing the dura can be quite difficult. It is usually performed using very small needles and sutures and specialized, fine-tipped grasping instruments. These instruments are necessary to hold together the incised or torn margins of the durotomy while the curved needle is passed through the two opposing dural margins or edges. The needle tracts or holes frequently create additional puncture sites through which CSF may leak or even squirt out. To make matters even more complex, the dura is protected by being surrounded with bony coverings such as the skull or the neural arches of the spine. Therefore, in order to operate on the brain or spine, bone material must be removed from the surgical site.
Closing the durotomy site also requires the removal of additional bone material, the extent of which relates generally to the space required to pass the curved needle through the incised dural margins. The margins which are torn or ragged result in excessive bleeding inside and around the dura thereby bringing blood into the surgical field and partially obscuring the durotomy surgical site.
A simplification of the durotomy closure procedure has been provided by United States Surgical Corporation (USSC) with small "C" shaped clips made from surgically implantable grade titanium. These clips are dispensed from a miniature surgical instrument called a clip applier also made by USSC. The clips do not perforate the dura but rather, hold the dural margins tightly together to halt the leak and promote dura regrowth. This instrument has been adapted from the larger clip appliers also made by USSC which are widely used in blood vessel surgery. The dural closure clips are generally available in sizes of 1.4 mm, 2 mm and 3 mm (outside diameters). Simple holding forceps are also provided by USSC to hold the durotomy margins together while the clips are being applied. An additional instrument is provided for opening and removing the clips.
Notwithstanding the ease of use of the dural clip applier and the holding forceps, suitable closure of the dural margins prior to applying the clips can still be a difficult task. The embodiments of the present disclosure solve these and other associated problems and provides a simple and easily applied instrument to draw together the dural margins while retaining the necessary nerve filaments and fragments inside the dura as it is closed by the surgeon.